Nadal, one of the top contenders for the postponed Kentucky Derby, was retired Thursday after breaking his left foreleg during a workout at Santa Anita Park in Arcadia, Calif.
The Bob Baffert-trained 3-year-old, who won all four of his races, underwent X-rays after running a half-mile, and a condylar fracture was detected. He then had an operation to insert two screws into the leg.
"We've already done the surgery. He's back in his stall, he looks good," Baffert said, according to the Daily Racing Form.
"He got a very serious injury today, and he's fine now," co-owner George Bolton told the Louisville Courier Journal. "We're lucky. We got four great races out of him. ...
"The good news is this injury was found, right? It could have been catastrophic. (Baffert) called me this morning and said, 'He's done.' I couldn't believe it."
The horse had been training for the June 20 Belmont Stakes, which will be the first event in the Triple Crown this year due to the coronavirus pandemic.
Nadal won the San Vicente Stakes at Santa Anita in February, and he won one of the two heats of the Grade 1 Arkansas Derby earlier this month. He was on top of the points race for qualification in the Kentucky Derby, which was postponed from May 2 to Sept. 5.
Nadal also sat atop the National Thoroughbred Racing Association's poll of 3-year-olds as of Tuesday, just ahead of Tiz the Law and Charlatan. TwinSpires.com's Joe Kristufek had him as the Derby favorite as of last week.
The misfortune for Nadal continues a rough week for Baffert. Charlatan, another horse that he saddles, tested positive for lidocaine on May 2, according to multiple media reports on Wednesday.
Charlatan is ranked fourth in Kentucky Derby points. However, the positive test could result in a disqualification from his win in the other heat of the Arkansas Derby, which could affect his eligibility for the Kentucky Derby.
Baffert requested a second round of testing on the horse's samples.
A 3-year-old filly that Baffert trains, Gamine, also reportedly tested positive for lidocaine, a regulated anesthetic widely used in equine medicine.
--Field Level Media